Colloid mill with pre-cutting attachment



March 28, 1961 K. H. GUSTKE COLLOID MILL WITH PRE-CUTTING ATTACHMENTFiled Nov. 8, 1956 5 Sheets-Sheet l 4 u "u \l INVENTOR.

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HUI Hwwwflwnw \l T n. Q i IIT 5 \7/ :13 r J m. 6 7w 1 m II, t 7 Afr 1 Ks d w COLLOID MILL WITH PRE-CUTTING ATTACHMENT Klaus HerbertGnstke,Rastatt, Baden, Germany, assignor to Probst & Class, Rastatt, Baden,Germany, a firm of Germany Filed Nov. 8, 1956, Ser. No. 621,141

Claims priority, application Germany Nov. 16, 1955 2 Claims. (Cl.241-101) The present invention relates to colloid mills with grindingrotors mounted in stationary housings, and more particularly to meansattached to the inlet portion of the mill for preparing the material tobe milled by pre-cornminution.

Colloid mills operate with suitably shaped and arranged serratedgrinding discs or bodies of silicon carbide or special steels. In suchknown mills, the adjustment of the comminuting space or gap definedbetween stationary and rotating conical grinding elements may beeffected, for instance, by axially moving the elements in relation toeach other, the fineness of the milling depending, in part, 011 thewidth of the comminuting gap. Colloid mills of this type have been usedfor finest comminution, homogenizing, dispersing, and emulsifying ofdifferent materials. However, the grain size of the material to becomminuted may not exceed certain dimensions (for instance, about mm. indiameter), depending on the composition and tenacity of the material tobe ground. Therefore, to avoid clogging and stoppage of the mill, it isvery often necessary first to coarsely comminute the material in aspecial crushing mill before it can be ground in the colloid mill.

It is the principal object of the present invention to provideeffective, efficient and economical means to prepare material forcomminution in a colloid mill.

It is a more specific object of this invention to provide a demountableattachment at the inlet portion of a colloid mill for pre-cutting orpre-cmshing material to be ground therein.

It is a further object of the invention to mount such a p re-cutting orpre-crushing attachment in such a manner that it may be easily mountedand detached by an operator.

It is also an object of the invention to drive the precutting orpre-crushing attachment directly by the shaft which rotates the grindingrotor.

It is another object of the invention to mount the precutting orpre-crushing arrangement so that the comminution space or gap of thecolloid mill may be adjusted without interference by the attachment.

The above and other objects, features and advantages are accomplished inaccordance with the present invention by detachably mounting apre-cutting or pre-crushing device at the inlet portion of a colloidmill and operating the device directly by an extension of the rotatingshaft of the mill rotor.

The invention will be more fully explained in conjunction with thefollowing detailed description of certain Ice Mensa Mar. 28,1961? Figs.2a and 2b show convex and concave surfaces, respectively, of the baseplate;

Fig. 3 is a top view illustrating certain details of the base plate andknife holders of the embodiment of Fig. 2;

Fig. 4 is a perspective view of the paddle wheel c0nveyor; 7

Figs. 5 and 6 are transverse sections of the knife and apertured baseplate; 7

Figs. 7 and 7a show a detail of the apertured base plate with an obliqueaperture and tooth;

Fig. 8 illustrates a horizontal colloid mill; and 1 2 Figs. 9 and 9ashow a detail of the apertured base plate with an oblique aperture. V

The top portion of the colloid mill itself, which forms no part of thepresent invention, is schematically illustrated. The colloid mill may,but need not be, of the general type shown in U.S. Patent No. 2,749,053or in- U.S. patent application Serial No. 562,542, filed January 31,1956, by Klaus Gustke and Erich Kuhls, and includes 9 to receive thematerial to be ground from the inlet.

portion of the mill. As is known per se, the grinding rotor portion 7has apertures in its walls through which the material to be ground isthrown into the comminuting gap be centrifugal action. Rotor portion 8is'keyed or otherwise fixedly mounted on operating shaft 10 whichisrotated by a power source, such as a motor (not shown); The groundmaterial leaves the comminuting gap by mill outlet 11. All of thisstructure is known'per se and forms no part of the present invention,except inasmuch as it cooperates with the pre-comminuting or cuttingdevice presently to be described.

For the purpose of mounting the pre-cutting or precrushing attachment inthe inlet portion of the mill, an extension shaft 12 is fixedlyconnected to and rotated with operating shaft 10. The extension shaft,which also carries and rotates grinding rotor portion 7, may beconnected to shaft 10 by any suitable means, such as by a threaded orwedged joint. Extension shaft 12 carries and rotates rotating knives 13and 14 of the pre-cutting device, as will be more fully describedhereinafter.

A different connection between the operating and extension shafts isshown in Fig. 1a. Here, shaft 10ais connected with shaft 12a by means ofa mortise-and tenon joint, shaft 12a carrying the pre-cutting structurewithout the interposition of a sleeve 29 being keyed to the shaft, as inthe embodiment of Fig. 1.

In the embodiment of Fig. 1b, the mortise-and-tenon joint of Fig. la isreplaced by splines 32.

As shown, the pre-cutting device is mounted in a hous An apertured baseplate 22 is arranged between knives 13 and 14 andreplaceably mountedbetween flanges "17 and 20, respectively, of housing portions 15 and 18.Base plate 22 is held against rotation by one or several pins 1 ereby tp ate is a ache to flan e 17 .Eh top and bottom portions 'of thelfdusingare detachably connected by wing screws 23 or similar connecting deviceswhich can be easily connected and disconnected. Base plate 22 may bemounted on extension shaft 12 by means ofball bearings'24 although nosuch bearing may be necessary, depending on the type of shaft used.

' Fig. 2 illustrates a different embodiment of the base plate; As shownin the drawing, the plate comprises two portions 22a and 22b, eachprovided with holes or slots 25a and 25b, respectively. By rotating thetwo plate portions in relation to each other, the holes'of therespective portions may be brought into and out of registration, thusserving to narrowor widen the passages through which cut material maypass. Thus, the desired grain size may be regulated even during thepre-comminuting step. Otherwise, the base plate of Fig. 2 operates inthe same manner as the single plate illustrated in Fig. 1.

As will clearly appear from the drawing, top portion 18 of thepre-cutting device housing may be easily detached and, after removalthereof, the entire pre-cutting device assembly may simply be lifted offthe extension shaft 12. After the pre-cutting device is thus removed,the housing top portion 18 may be replaced in position and the colloidwill operate without a'pre-cutter when material is charged into the millthrough hopper 28 attached to the top of portion 18 in communicationwith aperture 19 thereof.

As shown in Fig. 1, the pre-cutting device assembly comprises a sleeve29 keyed to the extension shaft 12 at 30. The removably mounted sleeve29 carries knife holder 26 arranged above the base plate and holdingknives 13 as well as impeller or paddle wheel 27 (see also Fig. 4)arranged below the base plate, the impeller carrying knives 14, ifdesired (see Fig. 1). The knife holder is keyed to sleeve 29 at 261 andmay be axially moved on the sleeve by adjusting the screen cap 31.

Fig. 2a is identical with Fig. 2, except that the plate portions 22a and22b have convexly curved surfaces.

Fig. 2b is similar to Fig. 2, except that the base plate 22:; consistsof a single portion (like the plate shown in Fig. 1) which has concavesurfaces, giving the plate a saucer-like appearance. Also, there is onlya top knife 13 and no knife below the base plate, the pre-comminutedmaterial falling through the base plate being seized by paddle wheel 27and directed to inlet 9.

Fig. 5 is a transverse section through knife holder 26 attached to knife13 by means of threaded bolt 33. 'As shown, the knife holder has apointed edge 34 which seizes and cuts the coarse material fed throughhopper 28 and then directs this 'pre-cut material to the cutting edge 35of the knife which is formed with a concave channel 36.

Fig. 6 shows a knife of the identical shape but, in this instance, theknife holder and knife form an integral unit. Also, the apertures inbase plate 22 are obliquely inclined instead of being vertical, as inthe arrangement of Fig, 5. Fig. 7a is a plan view of an oblique baseplate aperture with recess 37.

' Fig. 7 is a cross-sectional view taken along the line 7--7 of Fig. 7a.

Fig. 9a is a plan view of another oblique base plate aperture and Fig. 9is the cross-sectional view taken along the line 9-9 of Fig. 9a.

As shown in Fig. 3, the position of the knife holder 26 may be radial(26a), tangential (26b) or spiral (26c). Knives 13 are so arranged thatthey have actually two cutting edges 34 and 35, one of which seizes thematerial to be ground, presses it against base plate 22 and pre-cuts it,while the other cutting edge glides along base plate 22 and cuts thematerial as it enters the apertures in the plate. Fig. 3 also showsthat'the surface ofthe base plate may be serrated or otherwise roughenedto further the pre-cutting and pre-comminuting effect.

Paddle wheel 27 on the opposite side of base plate 22 .maycarry knives'14 in engagement with the base plate as shown in Fig. l. The lowerknives may be omitted as shown in Fig. 4. The material passing throughthe apertures in the base plate is again comminuted or cut Where knives14 are provided. Knives 14 may be positioned similarly as knives 13,i.e. radially, tangentially, or spirally. Paddle wheel 27 is somewhatsimilar to a snail which tapers downwardly, the paddles replacing theturns of the snail housing. The structure of the paddle wheel serves asa screw conveyor for the pre-cut material to the colloid mill proper.Paddle wheel 27 as well as knife holder 26 may be keyed or wedged tosleeve 29 so that they may be axially adjusted at will if suchadjustment is desirable due to a corresponding adjustment of thecomminuting gap in the colloid mill, for instance. Only base plate 22 isfixed against axial movement by being mounted etween flanges 17 and 20of housing portions 15 and 18 so as to fix the position of knives 13 and14 in relation to the base plate.

Base plate 22 may have the form of an annular disc, as shown in Fig. 1,or it may be frusto-conical, as illustrated in Fig. 2. It may also havea concave (Fig. 2b) or convex (Fig. 2a) surface. Convex base plates areused when the material to be ground is to be given a specific directionor if space conditions force such a structure since it is evidentlydesirable to make the cutting surfaces as big as possible withoutincreasing the dimensions of the precutting device unnecessarily.

As will be clear from the above description, the appa ratus operates asfollows:

Material to be milled is charged through hopper 28 into the pre-cuttingchamber and is cut therein by rotating knives 13. The cut materialpasses through the apertures in base plate 22, is seized by knives 14,and is again comminuted. Paddle wheel conveyor 27 transports theprecomminuted material into cavity 9 of the rotor portion 7 wherefrom itis centrifugally thrown into the comminuting gap. The finely milledmaterial leaves the comminuting gap by outlet 11.

If and when it is desired, the comminuting gap may be adjusted byrotation of adjustment ring 6 without interference by the pre-cuttingattachment. If no precutting is needed, cover portion 18 is lifted andsleeve 29 carrying the pre-cutting device is removed fromextension'shaft 12, whereby the colloid mill may be charged and operatedwithout pre-cutting of the material.

While the mill has been described as an upright mill, it will be evidentthat it could operate identically in horizontal position, as illustratedin Fig. 8. In this mill, the cover portion 18a has the shape of a funnelto direct the material fed through hopper 28a to the pre-cutter. Thepre-cutting and milling arrangement is identical with that illustratedin Fig. 1 and need, therefore, not be described again. Bevel gearing 40in gearing box 29 connects operating shaft 10a with shaft 41 of electricmotor '38. Obviously, the electromotor itself could also be horizontallymounted with its shaft in alignment with operating shaft 10a, in whichcase the bevel gearing would be eliminated.

As will be seen from the above, the apparatus of the present inventionprovides a single machine wherein milling may be continuously effectedfrom the stage of large particles to the very finest grains withoutinterruption, the desired fineness being adjustable by regulating thecomrninution gap in the colloid mill itself. Thus, the pre-cuttingattachment replaces a separate coarse precu'tting machine. In view ofthe easy attachment and detachment of a few elements only, such anapparatus has the further advantage of being usable as a colloid mill,'when the pre-cutter is detached, and a crushing mill, when'thepre-cutter is attached and the comminution gap, is opened wider. Anyin-between adjustment can equally simply be effected. If desired, theapparatus may be built into a conduit system to receive and dischargematerial from and to pipes in communication with the mill inlet and milloutlet.

While the invention has been clearly described and illustrated inconnection with certain preferred embodiments, it will be obvious to theskilled in the art that many modifications and variations may beeffected, particularly after benefiting from the present teaching,Without departing from the spirit and scope of the invention as definedin the appended claims.

I claim:

1. A mill comprising, in combination, a mill housing, a stationaryfrusto-conical annular milling element axially slidably mounted in saidmill housing, a rotary frustoconical milling element mounted Within saidannular milling element, a comrm'nuting gap being formed between saidmilling elements, the rotary milling element defining a central inletcavity for material to be ground in said comminuting gap, the materialbeing centrifugally thrown into said gap through aperturesin the rotarymilling element upon rotation of the rotary milling element, shaft meansjournalled in said mill housing for rotatably mounting the rotarymilling element, an extension shaft fixedly connected to said shaftmeans and rotatable therewith, rotary adjusting means connecting thestationary milling element with said mill housing for regulating theaxial position of said element thereby to control the width of thecomminuting gap, a stationary casing mounted on,

said stationary milling element above said adjusting means, a coverremovably mounted on said casing, the casing and cover forming ahousing, said extension shaft extending through the inlet cavity intothe housing, a removable sleeve member keyed to the extension shaft forrotation therewith, a non-rotatable apertured base plate mounted on thesleeve member between the casing and the cover, knife means keyed tosaid sleeve above the base plate for rotation with the sleeve, and knifemeans keyed to the sleeve below the base plate for rotation with thesleeve, both knife means cooperating with the base plate for shearingaction therebetween.

2. A mill comprising cooperating stationary and rotary milling elementsforming a comminuting gap therebetween, shaft means rotatably mountingsaid rotary milling element, inlet means for feeding material to beground to the comminuting gap, a shaft extension fixedly connected tosaid shaft means and rotatable therewith, a stationary casing mounted onsaid stationary milling element, a cover removably mounted on saidcasing, the casing and cover forming a housing, said shaft extensionextending through the inlet means into said housing, and cutting meansdetachably mounted on the shaft extension in said housing, the cuttingmeans comprising an annular apertured base plate mounted againstrotation about said 1 shaft extension and between the casing and thecover,

and knife means mounted on the shaft extension for rotation therewith onat least one side of said base plate, the knife means cooperating withthe base plate for shearing action therebetween, and comprising a knifeholder keyed to the shaft extension above the base plate and a pluralityof knives in said knife holder, and a paddle Wheel material conveyorkeyed to the shaft extension below the base plate, said paddle wheelcarrying a plurality of knives with cutting edges cooperating with theplate and knife ends conforming to the casing.

References Cited in the file of this patent UNITED STATES PATENTS 14,002Stout Dec. 25, 1855 746,275 Bowsher Dec. 8, 1903 1,687,886 Phillipp Oct.16, 1928 2,734,728 Myers Feb. 14, 1956 2,749,053 Rieth June 5, 19562,840,318 Schnell June 24, 1958 FOREIGN PATENTS 471,848 Canada Mar. 6,1951 534,013 Belgium Dec. 31, 1954

